This invention relates to an electrode for medical applications, and more particularly to an implantable cardiac cardioversion/defibrillation electrode.
Electrodes implanted in the body for electrical cardioversion or defibrillation of the heart are well known. More specifically, electrodes implanted in or about the heart have been used to reverse (i.e., defibrillate or cardiovert) certain life-threatening cardiac arrhythmias, where electrical energy is applied to the heart via the electrodes to return the heart to normal sinus rhythm. See, for example, commonly assigned U.S. Pat. No. 4,291,707 to Heilman, relating to a planar patch defibrillation electrode, and pending U.S. patent application Ser. No. 07/334,652 entitled Cardiac Defibrillation/Cardioversion Spiral Patch Electrode, filed Apr. 10, 1989.
The Heilman patent specifically discloses an implantable cardiac electrode comprised of a planar conductive material insulated completely on one side and partially on its other side. Apertures are provided around the insulated perimeter of the partially insulated side of the electrode to provide for efficient and uniform energy transfer to the heart tissue by eliminating the so called "edge-effect".
The pending application Ser. No. 07/334,652, relates to a spiral patch electrode comprised of a elongated conductor preformed to adapt a spiral planar patch configuration when deployed on or about the heart surface.
The amount of energy delivered by the electrodes to the heart during defibrillation (or cardioversion) depends on the placement of the electrodes and the ability of the electrodes to distribute the energy uniformly throughout a major portion of the heart. This energy is called the defibrillation or cardioversion energy.
For purposes of the following discussion, no distinction will be made between cardioversion and defibrillation, although the respective energy levels and timing sequences may differ. Both will be referred to as defibrillation.